/* body {
  background-size: 100% 100%;
  background: url("../images/jirx.jpg") 0 / cover fixed;
}
main {
  background: hsla(0,0%,100%,.3);
  border-radius: 5px;
  position: relative;
} */
main::before {
  /* 用x-index控制毛玻璃在文字上还是下*/
  /* z-index: -1;
  content: '';
  border-radius: 5px;
  position: absolute;
  top: 0; right: 0; bottom: 0; left: 0;
  background: rgba(255,0,0,.3);  */

  /* content: "";
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  filter: blur(20px); */
}
body, main::before {
  background: url("../images/jirx.jpg") 0 / cover fixed; }
 main {
  position: relative;
  background: hsla(0,0%,100%,.3);
  overflow: hidden;
 }
 main::before {
  content: '';
  position: absolute;
  top: 0; right: 0; bottom: 0; left: 0;
  filter: blur(20px);
  margin: -30px;
 }